Present-day laser-induced damage technology gives a chance to produce many laser-induced damages of small sizes and smoothed shapes for short time. It gives a chance to reproduce high quality images inside transparent materials.
U.S. Pat. No. 6,322,958 to Hayashi; U.S. Pat. No. 6,333,486 to Troitski; U.S. Pat. No. 6,392,683 to Hayashi; U.S. Pat. No. 6,399,914 to Troitski; U.S. Pat. No. 6,417,485 to Troitski; U.S. Pat. No. 6,426,480 to Troitski; U.S. Pat. No. 6,490,299 to Raevsky et al. and U.S. Pat. No. 6,509,548 to Troitski disclose methods and apparatus for creation of small laser-induced damages of smoothed shapes.
U.S. Pat. No. 6,322,958 to Hayashi discloses a laser marking method and apparatus comprising focusing the laser beam radiated from the laser source at a converging point inside of a work member to form cracks of specific forms.
U.S. Pat. No. 6,333,486 to Troitski discloses a method and system for production of laser induced damage by generating breakdowns in several separate focused small points inside the etch point area.
U.S. Pat. No. 6,392,683 to Hayashi discloses a laser marking method wherein the split plurality of laser beams are focused onto a very small region of the inner portion of the object to be marked so as to cause degeneration of the very small region of the object to be marked.
U.S. Pat. No. 6,399,914 to Troitski discloses a method for creating laser-induced damages with reduced sharp star structure comprising: production of the special transparent material by introducing special kinds of impurities; and generating laser radiation and focusing it at predetermined points of said material so that the focal spot area contains at least one said impurity and laser energy exceeds the damage threshold of said material with the impurities at the focal area by a negligible amount.
U.S. Pat. No. 6,417,485 to Troitski discloses a method for creating laser-induced damages of smoothed shapes by controlling breakdown process development comprising: generating laser radiation having sufficient energy to induce a plasma condition at a point in said material; and directing said laser radiation at said point to generate said plasma condition and thereafter maintain said condition until sufficient total energy has been delivered to said material so that a resultant damage area of the desired sizes will be created.
U.S. Pat. No. 6,426,480 to Troitski discloses a method for creating small smoothed laser-induced damages of determined sizes with controlling their brightness without variation of their determined sizes.
U.S. Pat. No. 6,490,299 to Raevsky et al. discloses a method and laser system for producing laser-induced damages without star structure by specific laser radiation, which is the serial combination of both generation regimes: a Q-switched mode and a free-running mode.
U.S. Pat. No. 6,509,548 to Troitski discloses a method for creating small laser-induced damages, which is based on generation of the initial electron density in the relatively large volume, creation of the breakdown at a small part of the said volume and control of the energy amount enclosed inside the plasma.
U.S. Pat. No. 6,087,617 to Troitski, et al.; U.S. Pat. No. 6,605,797 to Troitski; U.S. Pat. No. 6,630,644 to Troitski, et al disclose methods and laser-computer graphics systems, which provide the creation of such laser-induced damage arrangements, which on the one hand, reproduce desirable information about given images and on the other hand, the arrangements do not give internal crash of the used transparent material.
U.S. Pat. No. 6,087,617 to Troitski, et al. discloses a computer graphics system for generates an arrangement of the potential etch points. The arrangement is based on the characteristics of the selected optically transparent material so if the number of the potential etch points exceeds a predetermined number, the system carries out an optimization routine that allows the number of the generated etch points to be reduced based on their sizes.
U.S. Pat. No. 6,630,644 to Troitski discloses a laser-computer graphics system for generating an arrangement of laser-induced damages, which enables to produce image with high resolution like a computer graphic image from which it is derived, with little fluctuation in gray shades, and without star point structure.
U.S. Pat. No. 6,630,644 to Troitski, et al. discloses a method for creating arrangement of damages for production of 3D laser-induced damage portrait with the space resolution, which is equal to the appropriate computer 3D model.
So Patents mentioned above disclose methods for creating an arrangement of laser-induced damages, which enables to reproduce high quality image inside transparent materials. One of the purposes of the present invention is disclose a method for creating an arrangement of small laser-induced damages to reproduce an interference pattern corresponding to the given hologram.
A number of materials for recording and reproducing holograms are also well known.
For example, U.S. Pat. No. 5,383,038 to Lawandy, et al. discloses a method for creating holographic optical memory using semiconductor microcrystallite doped glasses by the simultaneous injection of fundamental and second harmonic fields. More specifically, the disclosure pertains to a structure that exhibits SHG, the structure being comprised of, by example, borosilicate glass that contains CdS.sub.xSe.sub.1-x microcrystallites.
U.S. Pat. No. 5,759,721 to Dhal, et al. discloses a holographic recording medium comprising an acid generator capable of producing an acid upon exposure to actinic radiation; a binder; and at least one monomer or oligomer capable of undergoing cationic polymerization initiated by the acid produced from the acid generator.
U.S. Pat. No. 6,160,645 to Chandross, et al. discloses a holographic medium, which uses a photosensitive polymer medium. The shelf life of the photosensitive polymer medium is improved by hermetically sealing the polymer between glass plates.
U.S. Pat. No. 6,489,065 to Dhal, et al. discloses a holographic recording medium comprises (a) an acid generator capable of generating an acid upon exposure to actinic radiation; and (b) a polymer comprising a plurality of high refractive index moieties, a plurality of low refractive index moieties, and a plurality of acid-sensitive linking groups connecting the high and low refractive index moieties.
U.S. Pat. No. 6,558,788 to Butler, et al. discloses a transfer film for holographic images which is a multilayer structure including a core and at least one outer layer having a sufficient thickness for receiving a holographic image impressed into it.
U.S. Pat. No. 6,558,851 to Fjeldstad, et al. discloses optical medium for registration of holographic interferograms, where the media consists of three transparent layers where the bottom layer is a glass substrate, the mid layer is an electro-conductive film of tin dioxide, and the top layer is a thermoplastic photo-sensitive amorphous molecular semiconductor film made of a matrix, which has donor properties and forms transport bands for holes.
So Patents and publications disclosing methods for recording and reproducing holograms are based on materials with special light-sensitive characteristics. One of the purposes of the present invention is the disclosure of a method for recording and reproducing holograms inside ordinary transparent materials without special light sensitive characteristics by using small laser-induced damages.